Question

If a calibration curve of absorbance vs procaine hydrochloride concentration (mol L') is linear with the equation y = 240000x for the derivatised procaine, what is the value of the molar absorptivity coefficient (Emolar)? Assume that a cuvette with a pathlength of 3 cm was used. (1 mark) Y=240000 Emolar = _ L molo

Answer 1

Answer:

8000 L/ mol cm is the value of the molar absorptivity coefficient.

Explanation:

The slope of the absorbance- concentration graph is equal to the product of path length and  molar absorptivity coefficient.

$\frac{dA}{dc}=\epsilon l$

$\frac{dA}{dc}$= Rate of change of absorbance with respect to concentration

$\epsilon$ = molar absorptivity coefficient

l = Path-length

Given the slope of graph of absorbance vs procaine hydrochloride concentration.

y = 240000 x (linear equation)

Path length of cuvette = 3 cm

$A=240000 c$

$A=\epsilon c\times l=(\epsilon l)\times c$

$240000=\epsilon \times 3$

$\epsilon =\frac{24000}{3}=8000$

The units of $\epsilon = 8000 l/mol cm$

8000 L/ mol cm is the value of the molar absorptivity coefficient.